Color developers containing an aromatic primary amine color developing agent for the formation of color images are known and, at present, play a primary role in the formation of color photographic images. However, aromatic primary amine color developers have the problem that they are oxidized extremely easily by air or metals and it is well known that if a color image is formed using an oxidized developer, fog increases with sensitivity and gradation fluctuates, so that the desired photographic characteristics can hardly be obtained.
In particular, there is lately a tendency toward greater fluctuation of photographic characteristics during continuous processing with the requirement that processing time be shortened and, in some cases, the photographic images formed have a serious problem of being color-stained. This problem is often especially serious when time period for the desilvering step or the step of rinsing with water is shortened.
Various explanations for the fluctuation of photographic characteristics or the generation of color stains in continuous processing have been considered including the following:
(A) The color developer deteriorates with the lapse of time to cause fluctuation of the photographic characteristics along with adhesion of the oxidized product of the developing agent to the photographic materials being processed, generating color stain in the photographic materials.
(B) The color developing agent is carried over into a bleaching solution or bleach-fixing solution bath, where the agent is oxidized, generating fog or color stain.
(C) Substances are dissolved out from the photographic materials being processed into the color developer and accumulate therein, so that those substances adhere to the materials to cause a color stain thereon.
(D) The dyes or sensitizing dyes contained in the photographic materials are not washed out sufficiently, so that the developed materials are colored.
(E) The bleach-fixing solution or the subsequent rinsing solution deteriorates with the lapse of time to cause the generation of color stain.
In order to solve the above-mentioned problems of (A) and (B), an indispensable requirement is to improve the stability of color developers.
Hitherto, various preservatives and chelating agents have been investigated for their ability to improve the stability of color developers. For example, there may be mentioned, as preservatives, the aromatic polyhydroxy compounds described in Japanese patent application (OPI) Nos. 49828/77, 160142/84 and 47038/81 (the term "OPI" as used herein means a "published unexamined Japanese patent application"), U.S. Pat. No. 3,746,544, etc.; the hydroxycarbonyl compounds described in U.S. Pat. No. 3,615,503, British Pat. No. 1,306,176, etc.; the .alpha.-aminocarbonyl compounds described in Japanese patent application (OPI) Nos. 143020/77 and 89425/78, etc.; the alkanolamines described in Japanese patent application (OPI) No. 3532/79, etc.; the metal salts described in Japanese patent application (OPI) Nos. 44148/82 and 53749/82, etc. As chelating agents may be mentioned, for example, the aminopolycarboxylic acids described in Japanese patent publication Nos. 30496/73 and 30232/69, etc.; the organic phosphonic acids described in Japanese patent application (OPI) No. 97347/81, Japanese patent publication No. 39359/81, West German Pat. No. 2,227,639, etc.; the phosphonocarboxylic acids described in Japanese patent application (OPI) Nos. 102726/77, 42730/78, 121127/79, 126241/80 and 65956/80, etc.; the compounds described in Japanese patent application (OPI) Nos. 195845/83 and 203440/83, Japanese patent publication No. 40900/78, etc.; the organic phosphonic acid series chelating agents described in Research Disclosure, Nos. 18837 (December, 1979) and 17048 (June, 1978), etc.
However, even when the above-mentioned preservatives and chelating agents are used, the improvement of the stability of some color developers is often still insufficient. In particular, when a color photographic material having a silver halide grain emulsion in which 80 mol % or more of silver chloride grains are contained is continuously processed, the result of the continuous processing is often unfavorable in that the processing solution often flocculates or the photographic characteristics of the material would often fluctuate.
On the other hand, to counteract the above-mentioned problems (B) and (D), the technique of adding a 4,4'-diaminostylbene series brightening agent to a color developer to prevent color stain or edge stain of the photographic materials processed has been proposed and described, for example, in Research Disclosure, No. 20733 (July, 1981), Japanese patent application (OPI) Nos. 14280/79, 49537/84 and 72444/84, etc. However, all the brightening agents described in the above-mentioned publications have only a small effect and, in addition, they are quite ineffective when processing is carried out using an extremely reduced amount of replenisher for rinsing.
As mentioned above, an effective and sufficient technical means for preventing the fluctuation of photographic characteristics and the generation of color stains in a rapid and continuous processing procedure using a reduced replenisher has not as yet been found and, therefore, there has been a strong desire for an effective and sufficient technical means especially for totally overcoming the above-mentioned problems (A) to (D).